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Category: Diseases

Don’t miss the 2017 KSU Turfgrass Field Day – August 3rd

The next Turfgrass Field Day will be held on Thursday, August 3, 2017 at the John C. Pair Horticultural Research Center, Wichita.
The KTF Turf Field Days are a great way to see and learn about the turfgrass research at K-State first hand. The events are held annually in the summer at the turfgrass research locations of Kansas State University.

The Field Day qualifies for recertification credit hr for commercial pesticide applicators.

You can now Register and Pay Online at  https://2017turffieldday.eventbrite.com
or you can register by downloading, printing, and mailing go to the 2017 Field Day brochure.

Exhibitors can get more information from the Exhibitor Registration Form.

Schedule of the 2017 Field Day 
8:00 a.m. Registration (coffee, tea, donuts)
Visit Exhibitors
8:45         Welcome
9:00        Tour Highlights:

*Turfgrass Weed Control Update
*Turf & Ornamental Diseases
*Bermudagrass & Zoysiagrass Cultivar Selection
*Using Kansas Mesonet to Imrpove Accuracy in Landscape Irrigation
*Right Plant, FROM the Right Place
* Prairie Star Flowers
*Tall Fescue NTEP
*Turf & Ornamental Insect Control
11:30       Lunch

After Lunch

  • Equipment Demonstrations

If you have any questions, please contact,
    Christy Dipman 
    1712 Claflin, 2021 Throckmorton Hall
Manhattan, Kansas 66506
Phone: (785) 532-6173
Fax: (785) 532-6949
Email: 
Christy

 

 

A queasy feeling leading into summer – turfgrass root health

Got layers of organic matter in your putting greens? That stuff holds water, which holds heat, and serves as a “risk factor” for root health.

It’s another week with rain in the forecast in many parts of Kansas. We’ve talked about this before on the blog many times – root health is key to getting through our tough summer months.

Do you have drainage problems? Do you have a buildup of organic matter? How do your roots look now? Sites with “pre-existing conditions” are the first ones to crash when the weather gets nasty.

 

Moisture management can be tricky, but there are tips and tools to help you. Here are links to two articles from last year:

By Jack Fry: – general tips for water management:

https://blogs.k-state.edu/turf/good-water-management-will-help-get-greens-through-midsummer-stress/

By Dale Bremer – using moisture sensors:

https://blogs.k-state.edu/turf/water-management-on-greens-with-soil-moisture-sensors/

Reducing summer stress on putting greens:

I’ve mentioned this fungicide guide (below) many times over the years. One of my favorite parts is the section starting on page 6 about reducing summer stress. Quick, off the top of your head, how many practices can YOU think of to reduce summer stress? The guide lists SIXTEEN steps to consider. Maybe you can’t do them all, but I bet you can try at least one new thing you have not tried before.

Here is the link (scroll to p. 6 for the summer stress)
http://www2.ca.uky.edu/agcomm/pubs/ppa/ppa1/ppa1.pdf

Pythium root rot:

My excellent colleague at U of Missouri, Dr. Lee Miller, has recently posted some very helpful info about Pythium root rot. You can find those articles here:

http://turfpath.missouri.edu/reports/2017/update05_26_17.cfm

http://turfpath.missouri.edu/reports/2017/update05_11_17.cfm

Powdery mildew in turf

Turf powdery mildew thrives in shady sites during cool, humid weather. We have had a lot of cool, moist days with temps in the 50s and 60s which is perfect for powdery mildew. The disease is often temporary, disappearing when hotter, drier weather kicks in.

The following photos are courtesy of my excellent colleague Chuck Otte, County Extension Agent, Ag & Natural Resources, Geary County. He confirmed that the site is shady.

It’s a fescue/bluegrass blend. To my eye, it looks like the Kentucky bluegrass is affected more than the fescue.

This next photo is a super-zoom of powdery mildew through the microscope. The photo is from squash powdery mildew, not turf powdery mildew, but turf powdery produces similar structures – long chains of spores. The spores are blown by wind. When they land on a new, susceptible plant and IF conditions are right, they germinate and infect.

We see turf powdery mildew in spring and fall. A change to less humid, hotter weather will slow the disease.

Turf powdery mildew is one of the many diseases covered in the 2017 Turfgrass Fungicide Guide.

There are fungicides labeled, but for most of them little is known about the efficacy. The DMI fungicides have efficacy, but it can be hard to reduce disease once it is underway. Also, as I just mentioned, a shift in the weather will slow the disease. If a site has a chronic, ongoing powdery mildew options include improving airflow and sun exposure or renovating to a less susceptible type of turf or groundcover. Those cultural practices and site management tweaks are your best bet.

Anthracnose in shade trees

Here is a quick update from Ward Upham and the Horticulture News:

We are starting to see anthracnose on sycamore. Anthracnose is a fungal disease favored by cool, wet weather. Young leaves may wither and turn black. On older leaves, look for brown areas that follow the major veins of the leaves. In some cases, the petiole (leaf stem) is infected, which causes leaf drop. The leaf may look perfectly fine, so look for browned areas on the petiole.
In severe cases, the tree drops heavily infected leaves and may be completely defoliated. Healthy trees will leaf out again in a few weeks. Defoliation this early in the year does not affect overall tree health. Trees have plenty of time to produce new leaves and make the energy reserves needed to survive the winter.
Other types of trees that are affected by anthracnose include birch, elm, walnut, oak and especially ash. Anthracnose seldom causes significant damage to trees in Kansas, so chemical controls are usually unnecessary. Also, fungicides do not cure infected leaves. Applying fungicides now will not help.

 

For a detailed overview of anthracnose diseases of shade trees, you can check out the free online pdf version of Diseases of Trees in the Great Plains. I’ve mentioned this book before – it is a great resource!  Here is the link, and the anthracnose part is the section section, on p. 22 of the pdf.

Anthracnose is also covered in our Tree and Shrub Problems of Kansas book.

Spring turf disease potpourri

 

Wet, cool weather is favoring continued activity of large patch and other spring diseases. If you have not downloaded it yet, be sure to check out the 2017 fungicide guide from Vincelli et al.

For a superb update on large patch, dollar spot, spring dead spot, and root problems, you can roll on over to the Missouri Turf Pathology Report .

Here is some large patch in our research plots:

 

Just for fun, here is some fairy ring activity. I walk past this spot a lot, and those mushrooms popped out after a recent rain.

And also just for fun here are two panoramas of Rocky Ford! You can click to zoom and imagine birds chirping and a soft spring breeze in the air… ahhhh….

Zoysia research – a 2 minute video tour

Here is a brief tour of our zoysiagrass progeny evaluation plots. The study is in collaboration with Texas A&M, Purdue, and several other universities across the region. It is funded by the US Golf Association. PhD student Mingying Xiang is working on this as part of her dissertation research.

Here is the link to a brief video on YouTube.

Sorry about the wind noise! I tried on Monday, and it was even worse, so this is at least better than my first attempt. We can’t be too picky about the wind here in Kansas, right?

Here is a link to a post from last fall where we talk about the inoculation method.

And here is a checkerboard of inoculation points in Meyer zoysia, from a few years back:

Dothistroma needle blight in pines … or not?

We recently posted about pine wilt and pine tip blight. To round out the big three pine diseases, below are a few quick notes about Dothistroma needle blight. For a review of all three of these diseases, plus natural needle drop, you can check out Pine Diseases of Kansas. (Click that link to download a free pdf with lots of photos and management information.)

Dothistroma needle blight is common in Austrian and Ponderosa pine. It can occur on Mugo pine, too.

Dothistroma spends the winter in infected needles. During wet conditions in late spring/early summer the fungus infects new needles.

Here is a photo of the fungal fruiting structure – the little black lump peeking out from under a flap of needle tissue:

We have been seeing those in the past couple of months on needles that were infected last year. December through April is when those fruiting bodies start to pop, allowing us to make a diagnosis.

Those fruiting structures produce spores that spread in rain to infect new needles. This often occurs during wet, mild weather in late spring, early summer (but can occur all summer). Those needles eventually show a partial needle scorch, with the base staying green. Each needle is a little different, depending on where the fungus got in there. The photo below shows some needle spots and banding and then the browning (necrosis) from the infection point outward.

 

On a tree, this shows up as partial browning, then complete browning, of the needles one year back on the branch:

The older, needles eventually drop off, leaving just a one-year tuft of the newest needles. The branch looks like a broomstick or a lion’s tail:

The damage tends to start in the lower part of the tree and work its way up. The disease is more likely in older trees. Mature, overcrowded windbreak trees are susceptible. Normally, pines keep several years of needles. If all those inner needles drop the tree has less capacity to do photosynthesis and it can weaken. Each little needle is like a solar panel, and fewer solar panels means less energy.

What do you think about this tree?

It is a young tree, and the damage is more top-down, not bottom up. So the overall pattern does not seem right for Dothistroma. Remember – with Dothistroma the disease usually starts at the lower part and works up, with older trees more prone to the disease.

Let’s take a closer look. What do you see? Or NOT see?

The damage is pretty uniform, with each needle looking quite similar. Compare it to that photo farther up where each needle is a little different. Plus, there is no spotting/banding. My guess is this is environmental stress. Pines can definitely get the moisture sucked right out of them during dry winter winds.

To know for sure, samples can be submitted to our Plant Disease Clinic either directly or (even better) through your local K-State Research and Extension Office.

Need more details? Remember our publication about Pine Diseases in Kansas where you can find more information about diagnosing and managing Dothistroma and the other pine diseases.

Impatiens downy mildew – it’s still “out there.” K-State’s Prairie Star program can help you diversify your shade beds

It is April, and everybody has spring fever. As you plan your ornamental beds for the year, consider using a diverse array of species. Specifically, I’m talking about avoiding a monoculture of impatiens.

You might remember a few years ago when a disease called impatiens downy mildew (IDM) hit the scene. Here in Kansas we did not see the vast losses that occurred in states farther east, but a few sites got hit. IDM has not received as much attention recently, but it is still out there. I’m not saying don’t use impatiens at all, I’m saying you should consider some diversity in the landscape. Don’t put all your eggs in one basket.

Filling every shady nook and cranny with impatiens now may seem easy, but that easy may turn into “disease-y”, and you might look back and wish you had included more diversity.

The standard, typical impatiens, Impatiens walleriana, is highly susceptible to downy mildew. If the weather is conducive to disease (moderate temps, wet, humid), a bed of I. walleriana can get wiped out quickly. The plants lose all their leaves, with only a stand of stems left behind. The pathogen can survive year-to-year as a survival structure called an oospore. So, if you know you had IDM history last year you should definitely avoid impatiens in the same bed this year.

The two photos below show dense, white sporulation on the undersides of leaves. The leaves drop, and entire plants can lose their leaves quickly.

 

Other related species, such as I. balsamina and certain hybrids, exhibit good tolerance, and those are options. Breeders are working to develop more resistance. Stay tuned!

What else can we use in shade, besides impatiens? K-State’s Prairie Star and Prairie Bloom program highlights species and varieties that thrive here. You can scan through to see which species flourish in shade, and click on photos to check out the blooms and other traits. Begonias are one option, but there are other shade-tolerant plants to explore. At the Prairie Star website you can opt to print a pdf version of the list to carry with you to the garden center for easy shopping. Here is a link to some of the new additions for 2017.

If you want to read some more details about impatiens downy mildew you can check out this article by Margery Daughtrey in the online version of Grower Talks.

“Hey large patch, quit Mickey Mousing around”

This is just for fun. Check out what my colleague Dr. Jack Fry and our student Mingying Xiang found today. I’ve seen a lot of large patch over the years, but it has never stared back at me quite like this.

(Original photo by Mingying Xiang)

Or, maybe it is Minnie, since the women on the large patch team outnumber Jack two-to-one:

This patch is in Latitude 36 bermudagrass on a sand base, in a sports field location.

On a more serious note, as a reminder, the 2017 Chemical Control of Turfgrass Diseases is now available online, as Jared just posted about.

Just for fun, here are a few more photos from Dr. Fry. It’s like a Rorschach test – what do YOU see?

Butterfly patch?

 

Mitosis patch? (Telophase)

 

Valentine patch

Snowman patch?

Pine tip blight – Is it happening in a tree near you?

(by Megan Kennelly, K-State Plant Pathology)

I’m seeing some pine candles just starting to emerge. Are YOU seeing any shoot growth yet? Newly emerging pine shoots are susceptible to tip blight, so here is a yearly reminder of the nuts and bolts of this disease.

tip-blite
DSC_0008
The classic symptom of tip blight is stunting and browning of new shoots and needles, as shown in the two photos above.

 

Pine tip blight is a fungal disease that can affect Austrian, Scots, ponderosa, and mugo pines. The disease is most severe on mature trees (20 years or older). Repeated infections over several years can kill large sections of trees or entire trees. Here are some Frequently-Asked-Questions about tip blight.

1) What is the pathogen?

Tip blight is caused by a fungus that has been called both Sphaeropsis and Diplodia over the years. The current name is Diplodia. Don’t let the name changes trouble you. The most important consideration is to recognize the disease, and to be able to distinguish it from other pine problems such as Dothistroma needle blight or pine wilt. To learn more how to compare/contrast those diseases, you can check out this page: http://www.ksre.ksu.edu/bookstore/pubs/l722.pdf

 

2) When does pine tip blight occur?

Tip blight is a spring disease. The fungus survives the winter in previously-infected tissue. Then, during spring rains, the fungal spores splash around and infect the newly developing pine shoots (candles) just as they start to grow (usually in mid-late April).

pine tip blight spores
Pine tip blight spores in the microscope. Spores are spread during spring rains, and they infect new shoots.

 

3) What are the symptoms of pine tip blight?

 The symptoms become obvious in late May or early June when the infected shoots and needles are not growing right. The shoots are stunted, and the emerging needles are stunted and brown – see the photos at the top of this post. Small, sticky resin droplets often form on the infected needles. The damage usually starts in the lower branches and works its way up over several years. In trees that have been repeatedly infected for many years, damage is distributed throughout the crown.

In addition to infecting the newest growth, the fungus can invade older tissues when trees are highly stressed or if they are wounded (by hail, storm damage, etc).

DSC_0001
Tip blight can affect older wood along with the newest shoot tips. This photo shows both.
DSC_0022
In this tree, the tip blight fungus has invaded some older parts of the wood, resulting in major tree damage.

 

Interestingly, white pines are not susceptible to the tip blight phase, but they are susceptible to this “canker form” of the disease if they are wounded.

In late summer or fall, tiny black spore-producing structures (called pycnidia) are formed on the scales of 2-year-old cones — it looks like black pepper has been shaken onto the undersides of the cones.

tip blight on cones
Tip blight on cones. Click to zoom, and you’ll see black specks. Those are the fungal spore-producing bodies.

 

Tip blight can be confused with winter damage or infestation by the pine tip moth. However, winter damage usually causes shoot or needle death before the new needles emerge in the spring, and it is sometimes restricted to one side of the tree (the side facing the prevailing wind). Unlike tip blight, the tip moth causes a hollowed-out area in the tip/bud area, and the larvae are sometimes present. Plus, tip moth is more common in young trees. The timing and pattern of symptoms, and the age of the tree, can help you with the diagnosis.

In extreme cases tip blight can be confused with pine wilt. To avoid confusion, look carefully at the symptoms and compare them to the descriptions and photos here and in other resources. Pines can be infected with both diseases simultaneously. If there is any doubt, bring a sample to your local K-State Research and Extension office to be forwarded to the K-State diagnostic lab.

Managing tip blight:

4) Does pruning help?

 Removal of dead branches can improve the appearance of diseased trees but will not prevent infection. Many of the spores are produced on cones that remain attached to the tree. In addition, tissues that look healthy can secretly harbor the tip blight fungus. That is, there are “hidden infections” that we can’t even see. Usually, pruning for tip blight means pruning off lower branches first, since they tend to be the first to become infected. Then the pruning task moves up the tree as the disease progresses over the years. If a tree reaches a point where it is no longer pleasing or functional for the site, “one-cut pruning” (ie, tree removal) might be the best possibility.

 

5) What other tree care should I provide?

Trees should be adequately (not excessively!) watered  to maintain tree vigor. This will help a tree fight off tip blight on its own. When a tree is drought stressed it has less energy and resources to put into defenses against pathogens.

 6) Will a fungicide be effective?

 This is a tricky question. The trouble is, unlike smaller plants like wheat, tomatoes, or soybeans, there aren’t many studies out there to tell us about tip blight “thresholds.” As a general rule, if a tree has at least 30-50% of branches infected, the fungus is pretty well entrenched and it will be difficult for fungicides to reduce disease, even if used over multiple years.   And, if there is a lot of “canker” type infection in older wood, it is hard for fungicides to work. If a smaller portion of the canopy is affected, and it is mostly the “tip-blight” phase, fungicides are more likely to be successful over time. Finally, consider the aesthetics and site-enhancing value of the tree. In trees where the disease is caught early, and fungicides are used at the right time each year for multiple years, the disease can be reduced over time.

 

7) Okay, so what is the right time for fungicides?

If you opt to use fungicides, the critical time for fungicides is when the new shoots are expanding in the spring. If fungicides are applied at this time, new disease can be prevented. It is not a one-shot-deal, however, and not even a two-shot-deal. Fungicides will likely be needed each year to protect new annual growth. Each year, the first application should be made when new shoots start to elongate, which is usually around the third week of April. The tree should be sprayed again 10 to 14 days later, and possibly again 10 to 14 days after that if it is a wet year and the site has a history of disease. The timing should be adjusted slightly depending on host development in the spring, since every year is different. Spraying after this critical time will not be effective, because infection has already occurred and cannot be “cured.” Once you see symptoms it is too late. Every year I get a question or two from someone wanting to spray in later summer or fall, and that is not going to work.

8) What should I spray, and how should I spray it?

 Several fungicides are labeled for pine tip blight. Thorough coverage is essential. A high-pressure sprayer may be needed to deliver the fungicide to the tops of tall trees. Homeowners should consider using a professional tree care service, especially for large trees where getting good coverage is difficult. Some fungicides (active ingredients) are listed on the last page here:

http://www.ksre.ksu.edu/bookstore/pubs/l722.pdf

The user must read and follow all label instructions.

9) What about injections?

Fungicide injections have been studied, but so far results have been inconsistent/ineffective and injections are not recommended at this time.

Got more questions? Feel free to email me at kennelly@ksu.edu